Re: Bug#636292: MD5Sum mismatch is due to multiple DNS queries!
On Sun, 07 Aug 2011, Kurt Roeckx wrote:
> The new .debs are done first, so that if you get a Packages or
> Sources file, you can actually download the files mentioned in
> those files. They are directly copied to the correct place since
> they are new files and not updated files.
> Then the Packages, Sources, Release and other files are first
> all transfered, then moved to the correct place.
Well, that has two problems we have observed in practice:
1. Not all mirrors have up-to-date mirror scripts, and that
_does_ include mirrors selected for the multi-mirror aliases;
2. Mirrors in the same multi-mirror alias are not updated at the
same time, and it is very possible (especially in http
scenarios) to get metadata skew problems across mirrors even
when they are perfectly fine and internally consistent.
That doesn't even need a third issue (multiple DNS queries) to cause
problems, way too many users are behind http proxies and caches that
break things regardless.
Maybe we should start designing sequence tagging/generation tagging for
the metadata? If nobody has time to implement it right now, it would be
a damn fine GSOC project for 2013...
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot